This topic has been discussed before at this site, but there was never any agreement. I have a very specific situation that I hope I can get a concrete answer, including equations and a step-by-step solution in inch/pounds/seconds units. A steel flat panel 6" X 18" weighing 3.25 pounds pivoted and fell 4 feet (center of gravity) striking a person flat on the head. What was the force that struck the person? This was an actual situation that raised a lump on the person's head.